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floppy disk or $5 printed hard copy. 


NEW FEATURE COMING! 

I think it’s about time to do some 
elementary circuit analysis starting this 
month and continuing in the issues 
ahead. There are many slick and wicked 
circuits in the current crop of scanners 
on the market and if you know how they 
work, it might help you become a better 
hacker. At the least, you might be able 
to “copy” or emulate some of these 
circuits for your own hacking and 
experimenting needs around shop and 
shack. This month, we’re going to take 
a close look at the Low Battery Warning 
and Memory Retention circuits in the 
venerable PRO-2004/5/6 scanners. 

Each month, I’ll try to dissect and 
explain a new circuit from these and 
other scanners. Your preferences are 
very important, so if you have a pet 
peeve or favored circuit that you’d like to 
better understand, just let me know so I 
can put it on the list This offer is pretty 
much limited to scanners for which I 
have Service Manuals on file. If I don’t 
have the manual, you’ll be expected to 
provide it, else do without the analysis. 
Use postal mail, e-mail, fax, or the 
Hertzian Intercept BBS to get your 
request on the list. You can also register 
it by voice phone with Cindy during our 
normal voice phone hours, if you like. 

PRO-2004/5/6 

LOW BATT CIRCUIT 

EXPMINEL ) 

The Low Battery Warning indicator in the 
PRO-2004/5/6 is a work of art, and just 
complicated and mysterious enough to 
confuse many wannabe hackers. It also 
screams for a little improvement here 
and there, so let’s take a detailed look at 
the meat 'n taters of this circuit and see 
what can be done with it. It’s pretty slick 
and yet easily understood with just a little 
guidance. See the above drawing of the 
Low Battery Indicator circuit for the PRO- 
2005/6 which is identical to that of the 
PRQ-2004 except for circuit symbols. 


WORLD SCANNER REPORT 

A Journal of VHF-UHF Radio Technology & Engineering 

Published by COMMtronics Engineering at PO Box 262478; San Diego* CA 92196 

Publisher/Editor: W. D. Cheek, Sr* a.k»a+ "Dr. Rigormortis n 
Copyright © 1991-95 <A11 Rights Reseired> ISSN 1061-9240 

Volume 5, Number 2 $5.00 


PRO-2005/6 LOW BATT WARNING CIRCUIT 

(Identical for PRO-2004 though circuit symbols may differ) 


8.3v Supply 

A 


R-234 

470-k 


atQ-32 


Battery 


2.2-M 

R-235 



,0 

: 

*_- 9 


n 

!xl 


aaa.fiarni 


I 


14 H-PC324C * 
LM-324 ” 

trDTHTTrU 


R-233 

180-k 


.R-232 

,2.2-M 



To CPU Pin 31 
via CN-3, Pin 11 

A 


R-230 

564c 


Replace R-235 with a 4.7-meg 
resistor to raise the Low Batt 
warning level. See text. 


The heart of this circuit is IC-5, a basic 
op-amp of the 324 type....common as 
fleas on a junkyard dog. IC-5 is a 4- 
section op-amp, only one of which is 
shown above. The three remaining 
sections are used for other purposes in 
the scanner and are not relevant to this 
discussion. 

Op-amps are neat little chips with a 
variety of uses, from basic amplifiers to, 
in this case, voltage comparators! As the 
name implies, this circuit compares one 
voltage to another and makes a logical 
decision accordingly. Specifically, a 
preset reference voltage is applied to Pin 
10, the non-inverting (+) input, while the 
memory battery voltage is applied to Pin 
9, the inverting (-) input of the op-amp. 
In this specific configuration, the output 
at Pin 8 will be zero-volts so long as the 
battery voltage input is higher than the 
reference voltage input. As the battery 
weakens over the months, its voltage will 
steadily drop until at some point, it falls 
below the established reference voltage, 
at which time the output at Pin 8 goes 
high to Vcc or +8.3 volts. 

The CPU senses the low and high logic, 
and acts accordingly, or in this case, 
does nothing while the reference is lower 
than the battery voltage. When the 
output shifts to a “high”, the CPU senses 
it and turns on the Low Batt indicator in 
the display and performs a repetitive 
Beep until you change the battery. Now 
let’s look in detail at how this happens. 


The Memory Battery voltage feeds other 
parts of the scanner, but it also directly 
feeds the point shown in the diagram 
above. A fresh 9-v battery will produce 
at least 9.0 volts to this point. Now look 
at the two resistors, R-235 and R-232, 
each 2.2-MQ. Skipping the math for a 
moment, because they’re equal, each 
resistor will drop one half the batter 
voltage, or 4.5-v each for starters. This 
puts 4.5v at Pin 9 of IC-5. Now the 
math, lest some thing the battery will 
prematurely drain. Two 2.2-MQ resistors 
in series with the battery are the 
equivalent of 4.4-MQ. Using Ohm’s Law, 
where current equals voltage divided by 
resistance, we have 1 = 9* 4,400,000 or 
0.000002045 amps, or 2-^ia. There’s 
your answer: a 9-v battery can generate 
2-ixa for a year or more. No sweat. The 
idea was to get a sample of the battery 
voltage at Pin 9 of IC-5. So one half the 
battery voltage will always be at Pin 9. 

Now let’s look at the reference circuit 
We see where it is fed from the scanner’s 
+8.3v supply through R-234 and R-233, 
470-kQ and 180-kQ, respectively. Again 
using Ohm’s Law, 8.3v * 470-k + 180-k 
equals 12.8-jia. The voltage at Pin 10 
will be the voltage dropped across R-233, 
or: 180,000 x 0.0000128 = 2.3 volts. 
This, then, is the reference voltage at Pin 
10, which will not change. 

Now it becomes clear as the battery 
weakens from its starting 9 volts, exactly 
one half the voltage, whatever it is, will 

2/1/95-5:30 PM-Page ! 















be applied to Pin 9. When the voltage at 
Pin 9 gets to be 2.3-v, the output at Pin 8 
of IC-5 will shift from 0-volts to the 
supply voltage of 8.3 volts, (low to high). 
But wait!! 

The CPU is a 5-volt device and would be 
destroyed if punched with 8.3v logic. 
Ahhhh, but that’s what R-231 and R-230 
are for: protection! They form a voltage 
divider, just like the previous two 
examples, so we can once again use 
Ohm’s law: I = 8.3 * 33-k + 56-k or: I = 

8.3 89-k = 93-pa. The voltage that 
gets passed on to the CPU will be the 
voltage drop across R-230, or: 0.000093 
x 89,000 = 5.2 volts. Accounting for 
voltage drops within the chip, this will be 
about 5.0 volts as a logic-high for the 
CPU to turn on the Low Batt Indicator 
and to sound the warning Beep. 

That’s it, in its entirety, folks. Easy as 
pie. And what’s more, the improvement 
is now rather obvious. If the Low Batt 
indicator doesn’t go off until the battery 
has dropped to 4.6 volts (one half this is 

2.3 volts, remember?), then that battery 
is going to be mighty dead by the time 
the alarm sounds. Would it be better to 
have a little more warning in advance? 

Easy as 1-2-3. We’ll keep the same 
reference voltage of 2.3-v on Pin 10, but 
change the circuit of R-235 and R-232 to 
set the ratio that we want. My idea for a 
better alarm point is 6.0 or even 7.0 
volts....let’s say 7.0 volts. Ok, it will still 
take 2.3v or less on Pin 9 to trigger the 
alarm, but if we increase the value of R- 
235 to drop more voltage than R232, 
then that 2.3-v point will be reached 
sooner than under stock conditions. 
Let’s calculate how: 

Assuming 7-v is applied to R-235, and 
we want 2.3-v on Pin 9, that means R- 
232 will have to still drop 2.3-v. That 
leaves 4.7v to be dropped by R-235. 
Current equals 2.3v -i- 2,200,0000 = 

1.045-pa. That same current has to flow 
through the new R-235, which equals 
voltage divided by current: 

4.7v -r .000001045, = 4.49-MQ Cool! 
Let’s replace R-235 with a common 4.7- 
MQ resistor instead of fussing with the 
nonsense fractional value. Now let’s 
finalize the calculations: 

4.7-MQ + 2.2-MQ = 6.9-MQ total series 
resistance. Now, when 2.3v is dropped 
across R-232, 1.045-pa flows through it 
as well as through the new R-235: The 
voltage across the new R-235 at that 
time will be .000001045 x 4.7 MQ or 4.9- 
v. Finalizing, 4.9v in series with the 2.3-v 
equals 7.2-volts, the point at which the 
Low Batt Indicator will come on and the 
alarm will sound! We already 
determined that 4.5-MQ will trigger at 
7.0-v, and obviously, 2.2- MQ triggers at 


4.5-v, so there’s the pattern and the idea 
for how to raise your Low Batt Warning 
Indicator to a more reasonable level. 
You could substitute a 5- MQ or 10- MQ 
trimmer potentiometer for R-235 and 
adjust your own trigger point. Got the 
idea here? If not, ask me questions. 

PRO-2004/5/6 
MEMORY BATTERY 
EXPLAINED 


Here’s another one of those slick and 
wicked circuits that may have escaped 
your attention. It’s so simple that I 
missed it for a couple of years. The 
method by which the 9-v battery 
preserves your programmable memory is 
utterly wicked. Here’s its circuit from the 
PRO-2005/6, and again, it’s identical to 
that of the PRO-2004 though the circuit 
symbols differ. 

Ok, here’s the scoop. There are two 
conditions that we have to analyze in the 
below circuit. First, let’s assume the 
scanner is not connected to any DC or 
AC power. When this is the case, the 
CPU and SRAM memory chip will lose 
their memory contents unless +5v is 
somehow supplied. No sweat, the 9-v 
battery feeds through D-59 and R-247 
into IC-9, a very special CMOS voltage 
regulator that produces a steady, stable 
+5v output over a wide range of inputs, 
from about 5v to 15v or so. Hence, the 
9v battery is more than capable. 

The neat thing here is that IC-9 is so 
special that it consumes almost no 
current on its own, unlike most voltage 
regulators that drop 2VS-3 volts and need 
several milliamps just to operate. This 
would drain the battery in no time. IC-9 
is very special in that respect and can’t 
be found on just any street corner. It 
drops almost no voltage and consumes 
only a few billionths of an amp. When 


not operating, the CPU and SRAM 
memory also consume only a few 
billionths of an amp, so this may explain 
why the battery can last for six months or 
longer when the scanner is not connected 
to power. 

Continuing, resistors R-247 and R-256, 
ten ohms each, do little more than serve 
as current limiters to protect IC-9 in the 
event of a short circuit somewhere in the 
CPU area. These resistors are not 
important in the rest of this analysis 
because at the low currents we’re dealing 
with, they drop almost no voltage. 

This about wraps up the no-power 
condition of the memory battery analysis. 
Now, let’s look at what happens when the 
scanner is plugged into either AC or DC 
power, no matter whether it is turned on 
or off. 

A closer study of the schematic diagram 
reveals that the AC power supply is not 
switched by the on/off switch. If plugged 
into 110-VAC, the internal power supply 
is on full time and generating full DC 
voltage of about 12-13 volts. This DC 
voltage is switched, however, which turns 
the scanner on and off. However, a 
portion of that DC is fed to Q-33 to 
generate a 10-volt output into D-56. 

This same condition applies, even if AC 
is disconnected and an external DC 
supply is used. Q-33 is fed with full-time 
power so long as the scanner is 
connected to either AC or DC. This has 
the effect of applying about +9.2v to the 
cathode of D-56 and the anode of D-59. 

Voile! This turns off any possible current 
flow from the battery because the 
cathode of D-59 becomes more positive 
(+9.2v) than its anode fed by the (+9.0v) 
battery! A diode is an OFF switch when 
its cathode is more positive than the 
anode (reverse bias). Summary: the 
battery cannot pass current through D-59 
when the scanner is connected to any 
power! Yet, when it is disconnected, the 


2/1/95 — 10:54 pm — The "World Scanner Report" © 1991-95; Volume 5, No 2; Page 2 















anode of D-59 being more positive than 
the cathode, will conduct thereby 
allowing the battery to feed IC-9. 

\ 

Concluding, then, when AC or DC power 
is connected to the scanner, Q-33 
provides a continuous feed to IC-9, which 
in turn, produces the +5v “keep alive” 
power necessary to preserve the memory 
of the CPU and SRAM. If and when 
power is removed from the scanner, the 
battery instantly takes over the feed to 
IC-9. The major player in this action is 
D-59, which turns the battery feed on and 
off as needed. Interestingly enough, the 
PRO-2004/5/6 can lose both regular 
power and the memory retention battery 
supply for short periods (10-30 mins) 
without loss of memory. I suppose this is 
due to a number of capacitors in the CPU 
+5v line which retain their charge for a 


time. Thanks also to the extremely low 
“deep sleep” current requirements of the 
CPU and SRAM. 

There really isn’t anything to modify in 
this circuit, or that needs modification, for 
that matter. I did replace the equivalent 
of R-247 in my PRO-2004 with a 47Q 
resistor because in my tinkering, I 
inadvertently blew IC-9 a couple of times 
and got tired of paying Tandy several 
bucks a pop for the privilege. In my 
opinion, 10Q is a bit too small. On the 
other hand, I’ve not blown IC-9 since 
those first couple of times, so maybe this 
issue is not worth even a mention. It is 
something you can do if ever IC-9 gets 
popped for whatever reason. Otherwise, 
this circuit is best left alone and allowed 
to function as designed. 


II • : f 


The previous two circuit analyses literally 
scream for an explanation of the power 
supplies in the PRO-2004/5/6, so it may 
as well be done here and now where it 
fits best of all. The below diagram is a 
schematic of the PRO-2005/6 power 
supply, with superfluous circuits and 
traces deliberately erased to simplify the 
viewing and understanding of what's 
going on here. The PRO-2004 and PRO- 
2035 power supplies are very similar, but 
circuit symbols will differ, and there are 
minor differences here and there. 


TO LOGIC 
SECTION 



* TORL 4 
SECTIW 


BATTERY 


2 /U95 ~ 5:30 pm~ The "World Scanner Report" © 1991-95; Volume 5, No 2; Page?) 


































The AC Supply starts with the power 
cord that feeds directly to T-801 with no 
on/off switches in series. Thus, T-801 is 
energized any time the scanner is 
plugged into AC power. T-801 is a step- 
down transformer, reducing 110-vac to 
about 10-12 VAC. C-82 & C-81 are 
noise and spike filters. R801 is a high 
resistance shunt to chassis ground, 
probably for static dissipation. 

The low voltage AC is rectified into 
pulsating 120-Hz DC by full-wave bridge 
rectifier D-60, and filtered into a smooth, 
ripple-free 12-13 vDC by C-238 (and C- 
229). The path splits with one side going 
to the On/Off switch and the other to the 
emitter of Q-33 at the junctions of R-248, 
C-246 and D-58. DC power is full-time at 
this point where it is roughly regulated to 
about 9.2-v by Q-33, D-57 and D-56 for a 
feed to IC-9, the CMOS regulator for 
CPU +5v already explained in a previous 
section. 

The External DC Supply begins with a 
DC Adapter or power supply of your 
choice connected to J-6. Despite 
whatever the Owner’s Manual says, you 
can provide anywhere from about 10-v to 
15 volts DC at J-6. 

L-58, C-237 and C-246 are noise and 
spike filters while D-58 is for reverse 
polarity protection in case you miswire 
the plug for J-6. (Whew!) The center of 
the plug should be (+) and the shell (-) 
for whatever its worth. Like with AC, the 
DC input circuit is energized any time a 
source of power is connected. 

Power Supply Modification #1: R-249, 
as a current limiter, is a royal pain in the 
ass and should be jumpered across to 
eliminate it. You can also solder an 
identical resistor in parallel with R-249, or 
remove and replace it with a !4Q or IQ 
resistor rated at 1-watt or even two watts! 
R-249 at IQ rated at Vfc-watt, easily burns 
out for the dedicated hacker. In the 
PRO-2004, it's R-256 and in the PRO - 
2035 , it's R-223. 

A few punches on the calculator shows 
that R-249 will burn 
up with greater than 
700-ma. The normal 
current drain of an 
unmodified PRO- 
2004/5/6 is right at 
350-400 ma. Cool. 

But when an LED S- 
Meter is added and 
not too many more mods, we’re pushing 
that 700-ma break point. Some of my 
TurboWhoppers draw upwards of 1-amp 
or so. Back in my bench repair days, I 
found R-249 burned up on occasion in 
some scanners for no apparent reason. 
It’s best to modify R-249 as discussed 
and get it out of your hair. 


Power Supply Modification #2: The 
dedicated hacker will run into all kinds of 
power supply problems in time, so I 
always recommend removal of the AC 
supply altogether and running strictly 
from a source of external DC at J-6. 
Remove T-801, the AC power cord; and 
R-801. You’ll end up with lots more “real 
estate" for other mods, and your scanner 
will run cooler by a substantial margin. 

Continuing .The outputs of both the 

AC power supply and the External DC 
feed path meet at a common point in the 
scanner best described as the junctions 
of Q-33, R-248, C-246, D-58, C-238, and 
the hot side of SW-801, the On/Off 
switch. Basically, the scanner doesn’t 
care which feed you choose because it 
needs a very uncritical range of lOv to 
15-v to operate to precision perfection. 
This is possible thanks to the several 
sub-power supplies that we’ll analyze in a 
moment. 

The +12v feed goes through SW-801, the 
On/Off switch, and then through another 
current limiting resistor, R-229, a 2.2Q 
blue colored resistor rated at 1-watt. 
This could be a bit underrated for super- 
hacked scanners, but I’ve never seen one 
burn up, even under the heaviest loads, 
so there’s no reason to replace R-229 at 
this time. 

The switched end of R-229 (left end , 
closest to Q-32), makes for a great place 
to tap a source of +12v for mods and 
hacks. It stands up on raised legs and is 
very accessible. You can tap +12v from 
the other end of R-229, too, but that 
needlessly draws more current through 
the resistor, so take your +12v power 
from the switched end. 

The ON/OFF Switch is a physical part of 
the Volume Control, but has no other 
relationship to it. A gray cable with two 
wires runs from the switch contacts to 
the main receiver board and terminates 
at CN-8. The On/Off switch switches low 
voltage DC from either the AC supply or 
the External DC feed. Switched DC goes 
on to IC-7, IC-8, Q-32. the +30v supply 
and the Hold circuit, all discussed below. 

The Regulated Sub-power Supplies 
are uncaring of their input voltage levels 
within limits of reason and regardless of 
the inputs within that range, their outputs 
are fixed and stable. Basically, any feed 
of 10-16 volts will be just fine for any of 
these sub-supplies. There is only one 
power feed in these scanners that is 
subject to variation of input, and that’s 
the +12v feed to IC7, the Audio Power 
Amplifier chip, which really doesn’t care 
what its fed with....from a range of 8 to 
16 volts, it works just fine. Therefore, the 
exact DC feed voltage is not really 
important so long as the feed is capable 
of generating the current we need, which 


is about 400-ma for a stock scanner and 
upwards of 1-amp for us hackers. Your 
external DC Supply or Adapter should 
be rated at 12-14 volts at one amp, at a 
minimum. Unregulated will be ok. 

The +12v common feed from either the 
AC supply or the External DC supply 
goes no where else, aside from the Audio 
Amplifier, and to the inputs of the several 
sub-supplies that we’ll discuss next. 

The +8v Regulated Supply is the 
predominant provider in the PRO- 
2004/5/6 and PRO-2035. +12v feeds the 
collector circuit of Q-32, which is biased 
at its base by zener diode, D-54 to 
producing approximately +8.3v at the 
emitter of Q-32. Almost all the analog 
electronics in these scanners are 
powered from the emitter of Q-32. The 
specified voltage of +8.3 can vary a lot 
from one unit to the next, and I’ve seen 
as low as +7.8v to maybe +8.5v. This is 
rather odd, in my opinion, because the 
critical receiver mixers and RF front end 
can vary in performance over this voltage 
range. +8.2v seems optimal, but it’s not 
often seen without intervention. See the 
end of this article for a modification that 
allows you to optimize the +8v supply for 
your receiver. The +8v supply produces 
about 300-ma in most scanners. Q-32 is 
a TO-220 style NPN power transistor 
mounted on the receiver’s chassis next to 
IC-8. A lot of our mods and hacks use 
+8v, so it won’t hurt to solder a strip of 
PinLine sockets to the emitter of Q-32 for 
easy access to the +8v supply. 

There are two +5v regulated supplies 

in this scanner series, the first of which is 
IC-8, a standard TO-220-style 3-port 
7805 regulator, mounted and bolted to 
the receiver’s chassis for heat sinking. 
IC-8 is fed directly from the +12v line and 
outputs a constant, regulated +5v for 
most of the digital circuits in this scanner 
series. Since modern digital electronics 
are mostly CMOS, current requirements 
are very low, and in fact, in a stock 
scanner, IC-8 produces less than 100- 
ma. This is great for us, since a 7805 
regulator is easily capable of 1-amp or 
so, and most of our mods and hacks 
require a source of regulated +5v. It 
won’t hurt to solder a strip of PinLine 
sockets to the Out lead of IC-8 for easy 
access to the main +5v supply. 

The second +5v supply is IC-9 and has 
already been discussed earlier in this 
issue. There is no need for hacker use of 
this +5v source and it should not be 
tampered with under any circumstances. 

The +30v Supply is a real oddity in this 
modern age of low voltage systems, but 
something in the PLL section needs 30 
volts. The +30v supply is fed from the 
main +5v supply to one end of R-219 
where it goes into the basic "chopper” 


p = i 2 r 

— watt = I 2 x IQ 
2 

I 2 

V7=VJ 

I =.707 amps 


2/1/95-5:30 PM- The "WorldScanner Report" © 1991-95; Volume 5, No 2 ; Page A 












circuit of Q-24, Q-25, and T-9, where the 
+5v DC is chopped into a pulsating DC; 
stepped up by T-9; to about 30-vAC; 
rectified and regulated by D-51 and D-53, 
and filtered to a smooth 30-vDC by C- 
215, R-215, and C-214. That’s all that's 
worth telling about the 30-v supply. It 
has no interest to us hackers and it 
should not be tampered with under any 
circumstances. 

The “Hold” Circuit isn’t really a power 
supply, but there’s no good subject area 
to tell about it anywhere else. Since it’s 
located in the power supply area of the 
schematic, we’ll dissect it here. 

Let’s see what this sucker does before 
drawing any conclusions. Unswitched 
(continuous) +12v feeds the Hold Circuit 
at D-55 which with R-246, R-245, and C- 
244, forward biases Q-31 into conducting 
and driving its collector low. This “low” 
appears on the base of Q-31 to turn it off, 
where +4.4v then appears on the 
collector. This 4.4v can loosely be 
referred to as “+5v” high logic, which 
becomes pertinent as we follow the path 
from the collector of Q-30 to R-238 and 
the base of Q-29. This “high” appears on 
the base of Q-29, thereby shutting it off, 
making a “low” appear on its collector. 
Following the collector path of Q-29, we 
find that it goes to CN-3, Pin 9, where it 
is labeled “Hold”. Huh? 

Ok, so we follow that path onto the 
Logic-CPU Board where it goes to the 
CPU, Pin 17. Nothing else in the Service 
Manual is said about this “function”, but 
we can make some educated guesses 
after one more analytical effort. 

Since continuous +12v feeds this Hold 
function, let’s see what happens if power 
is removed from the scanner. In that 
case, Q-30, 31 and 29 cannot possibly 
conduct. But lo! The memory retention 
CPU +5v from IC-9 will place a +5v 
“high” at CN-3, Pin 9 via R-236, just the 
opposite from the low that is normally 
there when the scanner has any power 
applied to it! 

Aha! My conclusion is that when power 
is removed, this +5v high at CPU Pin 17 
causes it to go into “deep sleep " mode 
thereby minimizing the current required 
from the Memory Retention Battery. Not 
exactly a power supply, this "Hold” 
function, but now you know ail about it. 
I’d leave it alone, if I were you. It offers 
nothing of interest to the hacker. 

This concludes our first effort at circuit 
analysis of a popular series of scanners. 
If you have questions or if you want to 
see other analyses, then fire away. I’m 
your analyst. Just read page 1 in this 
issue first, and make sure I have the 
Service Manual for your scanner. I have 
many Realistics and a few Unidens. 


900 MHz CORDLESS PHONE FREQS 

The Jan-Feb 1995 issue of the “ American 
Scannergram ” shows the 900 MHz freqs 
used by Panasonic and Radio Shack 
cordless telephones. Apparendy there is 
no official band plan because as you can 
see, the only similarides are the band 
edges and 30 KHz spacing. 900 MHz 
phones from other manufacturers are 
reported to differ as well. 


Panasonic 

Radio Shack 

Ch 

Base Handset 

Ch 

Base 

Handset 

mm 


.926.100 

wm 

902120 

mmm 

02 


mmm 



926. ISO 

mm 

902.160 

mmm 

mi: 


mmm 

04 


926.190 

04 

902.210 

926.210 

06 


926.220 

05 

902.240 

926.240 

06 

902.250 

926.250 

06 

902.270 

926.270 

m 


mmm 

» 



m 


.926.310. 

mi 

mmm 


69 



mi 

902,360 

926.360 

EM 

902.370 

926.370 

m 

902.390 

926.390 

11 

902.400 


11 

902.420 

962.420 

12 

902.430 

926.430 

12 

902.450 

926.450 

mm 

14 v 

902 460 
902-490 

mmsm 

WMMSm 

m 

ii 

la 

926.480 

926.510 

m g 

902,520 

926.520 

m 

902.540 

mmm 

16 

902.550 

926.550 

16 

902.570 

926.570 

17 

902.580 

926.580 

17 


E2EI 

18 

902.610 

926.610 

18 

902.630 

926.630 

mm 


mi 

mmm 

mmmi 

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902.670^926^70 


m&mm 

;926;690 

mm 


mi 

rn/mm 

wmm 

22 

902.730 

926.730 

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902.750 

926.750 

23 

902.760 

926.760 

23 

902.780 

926.780 

24 

mm 

mm 

902.790 

SWSM20 

mmm 

926.790 

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936.8S0 

24 

wm 

mm 

902.810 
902.840 . 
902.870 

926.810 

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926870 

2 m 


926,880 

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28 

902.910 

926.910 

28 

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926.930 

29 

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926.940 

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926.960 

\EM 



WJM 

902.990 

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BSi 


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mm 

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mmmi 

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927.090 

34 

903.110 

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35 

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927.120 

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903.140 

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36 

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36 

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927.170 

mm 

mMM 

.927,180 

mm 

mmm 

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wm 

mm 

903.210 

903.240 

ipii 

38 

Mi 

mmm 

.mam.: 

927-23Q 

927.260. 

40 

903.270 

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903.290 

927.290 

41 

903.300 

927.300 

41 

903.320 

927.320 

42 

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927.330 

42 

903.350 

927.350 

mm 


mmm 

mi 

ftgasg; 

gill 

mm 

903,390 

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mm 


mmm 

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46 

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903.450 

927+420 . 
927.450 

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46 

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48 

903.510 

927.510 

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wm 

:903.540 

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; mmm 

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mm 

mm 

903.560 

903,590 

927.560 

927.590 

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903.620-:::: 

927,620 

52 

903.630 

927.630 

52 

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53 

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927.660 

53 

903.680 

927.680 

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927.690 

54 

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927.710 

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903,720 

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58 

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927,800 

927.830 

59 

903.840 

927.840 

59 

903.860 

927.860 




60 

903.890 

927.890 


Given die apparent hodgepodge freq 
assignments for this band, it’s probably 
best searched in 5 KHz steps. 

The “ American Scannergram” is the 
official publication of die All Ohio 
Scanner Club, 50 Villa Rd; 
Springfield, Ohio, 45503-1036. The 
“American Scannergram ”, while 

definitely focused on the state of Ohio 
and surrounding areas, is a nicely 
assembled and edited newsletter of wide 
appeal on the total spectrum of scanning. 
Its main appeal seems to be local 
frequencies and radio activities, but its 
also big on equipment reviews, scanning 
techniques and principles. It’s probably 
a “must” for the library of the compleat 
scannist. The motto of the AOSC is, 
God We Trust , All Others We Monitor 


Ill#:. *111®ATE- .1(11 

The PRO-2004 was replaced by the 
PRO-2005 in May, 1990. Radio Shack 
supports a product for five years after 
discontinuance. The “ Cinderella Hour •” 
is coming up fast. In fact, reader Bob 
Horvath reports Tandy is out of stock on 
the PRO-2004 Electroluminescent Panel, 
part # GE-85D-6067 given in WSR, 
V1N2P7. I’m not sure the bewitching 
hour has hit yet because I have been 
using an updated part number for a 
couple of years now: GE-86D-6011 

But, update your PRO-2004 Service 
Manuals on page 53, Item #43, to show 
this new part number. While you’re at 
it, it would be a good idea to order a 
spare EL panel or two, perhaps a new 
front panel, metal case and keyboard 
cover, and even a whole new keyboard. 


The below PRO-2004 items get the most 
wear and tear and will be impossible to 
find when Tandy cuts support of the 
PRO-2004. Tandy Parts: (800) 442-2425 


EL Panel 
Escutcheon Assy 
Cabinet 

Panel, Keyboard 
PCB Assy, Keyboard 
Knobs, Vo I & Squelch 
Knobs, Dimmer & SSq 
Antenna, Telescopic 
Vo I & Switch Ctrl 
Squelch Ctrl 


GE-86D-6011 
GA-86D-6385 
GE-86B-6360 
GE-86D-6359 
GA-86D-6320 
GE-86D-6356 
GE-86D6357 
GE-86D-6519 
5M1411-50KA-20A 
K1611008TE-10KC-20 


PRO-2004 Service Manual 20-119 


Refer to the service manual for anything 
else you might want to stock up on and 
order NOW or forever keep your peace! 


2/1/95 - 5:30 PM~ The "World Scanner Report" © 1991-95; Volume 5, No 2; Page 5 












































































































































































































BC100XLT/200XLT 
NiCd Battery Replacement 

‘ByQreg Strauss 

I've had my Uniden BC 100XLT for 
about 5 years, and the NiCd pack finally 
went out. So I called Uniden Parts and 
they wanted $37.00 for a new battery 
pack when all I wanted was the NiCd 
cells from the inside. Uniden won't sell 
the NiCd’s separately. I thought that it 
would be the cheaper route to go by 
soldering the NiCd’s in myself and not 
having to buy the whole pack (BP205). 

I looked through some electronic supply 
magazines for the replacement part 
(Sanyo Model #6N-550AA, 7.2V, 

600mAh) with no luck. Then I opened 
my Radio Shack catalog and found a 
cordless phone replacement NiCd pack 
(Cat# 23-193). This pack consisted of 
only 3 AA NiCd’s at 3.6 volts but at 
650mAh, which is 50-mAh better than 
the original. I bought two of these 
replacement packs from Radio Shack at 
$9.99 each for a savings of $17.00. Here 
is what I did to polish off the job: 

1. Disconnect power supply from rear. 

2. Slide the battery pack off the bottom. 

3. Remove the two screws from the 
bottom of the battery pack. 

4. Slide the front panel off of the battery 
pack. Be sure to pull the front panel 
straight off making sure you do not 
break the two top tabs. 

5. Slide the battery pack out of the case. 
(The 6 AA NiCd battery pack is 
encased inside heat shrink wrap,.) 

6. Cut the two wires as close to the 
battery as possible. (I kept the wires 
connected to the printed circuit board 
because it looked even more diffi cult 
to get that baby out) 

7. I removed some of the adhesive 
backed cushioning from the inside of 
the battery pack to make room for the 
new batteries. 

8. I took the two new battery packs and 
wired them in series, so I had a 
positive and negative lead left. 

9. Now the old battery pack end view 
looked something like this: 



with the batteries staggered. Keep 
this in mind when placing the new 
batteries in the case. 

10. Now this is the tricky part. Look at 
the inside of the battery pack lid. 
You will notice three round shaped 
tabs that were used to hold the old 
battery pack in place. You will need 
to trim these down in order for the 
new NiCd’s to fit I used my wire 
cutters which worked fine. 

11.1 connected and soldered the positive 
and negative leads and used heat 
shrink to cover them. 

12. Now remember the note in 9. You 
will need to place the separate NiCd 
packs in the case as such. 

13. Things may fit a little tight but it will 
work. Just be careful when replacing 
the lid back on the pack. I used some 
heat shrink to hold the new NiCd’s 
together but it was to big for the case. 
So I used a piece of tape to hole them 
together. 

I charged the new battery pack for 14 
hours and had an 11 hour use time. Not 
bad for a little work. 

Editors Comments : Nice piece of work, 
Greg, and very inventive! I included the 
BC-200XLT in the title of your article 
because the battery packs are the same, 
and the radios are mechanically the 
same for all practical purposes. Your 
procedure will generically work for most 
any “sealed” NiCd pack, too. For those 
who want to save even more bucks the 
individual cells shouldn ’t cost more than 
about $2 each, if you can find them. It 
might also be possible to beef up the 
pack up even more with use of nickel- 
metal hydride cells or heavy duty NiCds. 

Good places to start the search for 
individual replacement cells include: 

Alexander Batteries (619) 480-4445 
Sanyo Energy Co (619)661-6620 
Metro West (708) 354-2124 

Note thatMetroWest was big on supplies 
for the BC-100XLT and 200XLT, 
including a 1000-mAh rechargeable 
pack. I haven't heard anything from 
them in a long time and they may now be 
out of business. Something to check..... 

Also note that any beefing up of the 
NiCd cells must be accompanied by a 
beefed up recharger. The stock 
recharger may be fine for 50-ma more 
like Greg’s, but any more than that, and 
we have to redesign some of the 
charging circuit for higher current. 


FROM THE REAPERS 


FINDING THINGS IN PRQ-2006 

From: Thomas Nichols, Indianapolis. IN 

Hello, Dr. Rig. In regards to headphone 
audio for the 2004 and 2005 (Book #1, 
Mod #8, page 103), my 2006 has black, 
white and gray wires to the headphone 
jack, but no ground lug on jack, nor 
could I find the 270 ohm resistor. 

ED: In the PRO-2006, the black (middle) 
wire is the ground wire that runs from 
the shell of the head-phone jack to pin 3 
of CN-6. R-228, the 270f2 resistor, is 
physically connected between Pin 3 of 
CN-3 and ground, but it’s a chip resistor 
located on the bottom side of the main 
receiver board between C-222 & C-226. 
You do have the Service Manual, right? 

Also, on 2005 squelch improvement, I 
couldn’t find R-152 on my 2006. On the 
2006 there is a metal sheet (frame) with 
a PC board mounted on it covering the 
bottom where the IC-2 is mounted above. 

ED: R-152, 33-kQ, is a chip resistor 
physically installed between Pin 12 of 
IC-2 and Pin 1 of IC-10 on the bottom 
side of the main receiver board. There 
is an opening in the chassis nearby 
where you can access R-152 at an angle . 
The alternative is to remove the main 
receiver board from the chassis. On the 
other hand, IC-10 is a new addition to 
the PRO-2006 that eliminates the need 
for a Squelch mod. This has been 
treated in back issues of the WSR. 

Also, is there another BFO for mounting 
inside the set? 

ED: Not sure what you mean. There are 
no BFO *s for the PRO-scanners, period. 

Do you know about the new BC-9000? 

ED: It’s a piece of junk with all its bells 
and whistles coming from firmware; not 
hardware. Firmware is a cheap way of 
making a scanner (or other electronic 
equipment) look great. Caution advised! 

CALLER ID & SCANNERS ? 

From: Robert Pyle, Miamisburg, OH 

Is caller I.D. data transmitted by the base 
of a cordless telephone? Is it possible to 
connect a caller I.D. display to a 2006? 

ED: 1 don’t know much about CID because 
California won't allow it. People's rights 
here are subsidiary to the rights of Big 
Business, Government, and special interest 
groups, including all minorities and 
politicians. Some are more equal than others. 


2/1/95 ~ 5:30 PM~ The "WorldScanner Report" © 1991-95; Volume 5, No 2; Page 6 






























IMPOSSIBLE CELLULAR MODS 

From: Mrs. Gary Criblev, Thomaston, CT 

We have a PRO-2030 scanner. On 
Christmas day my husband wanted to 
restore cellular to our new scanner. He 
followed your instructions in V3N9, (Oct 
’93) but there is ng L201 jumper! Is 
there another modification for the newest 
PRO-2030? If so, could you put it in 
your next issue of the WSR. Thank you 

ED: Either it's there and you haven't 
found it, or else you bought that scanner 
AFTER March, 1994, when it became 
illegal to sell cellular-capable scanners. 
Existing stocks could be sold, but it's 
likely that Radio Shack pulled them or 
sold out before the deadline. New 
models imported or manufactured after 
3/94 cannot be "easily modified", and to 
the manufacturers, that means 
impossible. \Fraid you 're outa luck. 

From: David Cobb, Smithfield, NC 

Bill: I recently tried to unblock cellular 
coverage on a PRO-2026 AND A PRO- 
2030. I have done this before, but on 
these at the L201 location there was 
nothing but two empty holes in the 
circuit board. CAN YOU HELP ME? If 
you know any other way to restore 
cellular on these two units, please let me 
know. (Units were purchased 12/94). 

ED: See above. You 're S.O.L., too. 

COST OF BLUE LEDs DROPPING 
From: Fred Jacobson, Wenatchee, WA 
The price of Blue LEDs is getting lower. 
Check out Digi-Key’s newest prices! 
800-344-4539 


DigiKey Blue LED Prices 

Quantity^ 1 10 100 500 

100CR-ND T VA diffused .88 7.83 60.75 243.00 
101CR-ND T-l>/4 clear .88 7.83 60.75 243.00 
102CR-ND T-l diffused .88 7.83 60.75 243.00 
103CR-ND T-l clear ,88 7.83 60.75 243.00 

No min order, $5 handling charge on 
orders less than $25.00. Foreign orders 
add $5.00. No shipping US & Canada. 

ED: Great Boogley-Woogley! I'll say 
the price has dropped! Thanks! 

Service Manuals& BC-2500XLT 
From: Don Alesch, Jr., Menasha, WI 
Dear Bill, Just a quick note on your 
response to Mr. Schlegel on page 6 of 
V5N1. I did send you a Service Manual 
for the BC-2500 back in Sept 6 93. 
“Anyone” learned to teach this thing any 
tricks such as Mr. Schlegel requested? 

ED: Much of the time we 're sent partial 
and/or poorly reproduced copies of 
service manuals which get promptly 
flung without hesitation into the nearest 
circular file. I retain and study only full 
and complete copies in good, readable 
condition. In any event, I know little of 
the BC-2500XLT and have no idea if 
anyone else has probed it. It would seem 
not; else I'd have heard about it....I'm 
all ears to that sort of thing. © 

EXTENDED MEMORY MODS 

From: Todd Penney, Nova Scotia Can 

one buy a preassembled, pretested 6,400-ch 
extended memory board with the KMBC 
MOD-28 for the PRO-2006. If so, what 
would be the cost of this board and would 
Vols 1 & 2 of the Scanner Modification 
Handbooks be adequate for the installation? 


ED: At various periods of my Life, I sat 
down and made up reassembled circuit 
boards for the various mods. I've been 
so busy over the last couple of years that 
this has had to take a back seat and none 
are presently available other than the 
CE-232 Interface and the MOD-44 
Data/Tone Squelch. However, I have 
refined the Extended Memory mods to 
eliminate the need for boards and most 
wires altogether. This has been 
thoroughly documented in back issues of 
the WSR. The mods in my books are 
certainly more than adequate if you want 
to go that way; otherwise, research the 
WSR back issues and apply my new 
techniques for an incredibly easier job of 
most any Extended Memory mod. 

Within each of the 16 switchable blocks 
can you operate your scanner as a normal 
scanner of 400 channels with 10 banks? 
i.e. switch into Block 3, have only banks 
4,5, & 9 on and have 50 of 120 channels 
locked out? 

ED: Indeed! That's part of what my 
Extended Memory Mods are all about! 
The 16-Block, 6400-ch Mod is like 
having sixteen scanners lined up in a 
row with one useable at a time. 

PS What’s this about 25,600 channels? 

ED: That's what I mean about the back 
issues of the WSR! Try 64-Blocks of 
400-channels each for less work and 
equal or slightly higher cost than the old 
MOD-16 in my books! It's all in the 
back issues and cannot be repeated 
again soon for obvious reasons. The 
new techniques call for surface mount 
memory chips instead of DIP types! 


2/2/95 ~ 12.17 am ~ The ” World Scanner Report" © 1991-95; Volume 5, No 2; Page 7 


CQNfcieEH^liSUBS^^ 



NAME: 


USA RATES shown: Canada add 15%; Other Foreign +25%-surf/+50%-Air 


$ 



STREET 

1991 (1st Year, Jan-Nov/Dec)-10 ea $20.00 

1992 (2nd Year, Jan-Nov/Dec)-10 ea $21.00 

1993 (3rd Year, Jan-Nov/Dec)-10 ea $23.00 

1994 (4th Year, Jan-Nov/Dec)-10 ea $25.00 

$ 

$ 

CITY: STATE: ZIP: 

$ 

$ 

Work Ph: ( ) - Career or 



1991-94 (All the above) - 40 ea $79.00 

$ 

Home Ph:( ) - Profession 



lliiiiii 

TYPE OF SCANNERS » 

& Other Radios » 

Half Year 5 ea $15.00 

One Year lOea $25.00 

$ 

$ 

METHOD OF Check Cash M.O. Visa MstCard COD (+$8.50) 
PAYMENT » □ □ □ □ □ 

Amount Enclosed 

$ 

Two Years 20 ea $45.00 

. 

$ 

Credit Card 

Acct No:» - 

Amount Charged 
$ 

Scanner Mod Hndbk, Vol-1: $17.95 + $4.00 S&H * 
Scanner Mod Hndbk, Vol-2: $17.95 + $4.00 S&H * 

$ 

$ 

Name of Expiration / 

Issuing Bank Date: / 

Scanners & Secret Frequencies $19.95 + $4 S&H * 

* Canada US$9 S&H; Other Foreign US$9 S&H; all add extra for Air 

$ 

$ 

Signature Required (for credit card purchases) 

X 


CE-232 Interface Kit $194.95 + $5 S&H; All Foreign add 25%-surf 

Hertzian Intercept BBS Subs: $8/mo $15/3-mo $25/6-mo $40fyr $75/2-yr 

HOBBY RADIO BUYER’S DIRECTORY $14.95 ppd. surf 

Calif residents: Salaa Tax - 7.0% on all orders except WSR subs 

$ 

! VISA 

$ 


$ 

What else to tell us? 


$ 

US FUNDS PAYABLE TO; CQMmrtmm&tgtoMtin# 

L 


$ 
















































































STOCKING UP ON PARTS 
From: Tony Thornton, Mize, MS 

Hi Bill & Cindy; After Getting my PRO- 
2006 and using it for a while now, I can 
see why so much praise has been 
bestowed upon it in the scanner 
community/press. I chose the 2006 over 
the 2035 although I will most likely get a 
2035 later. 

ED: See the recent back issues where 
we covered the PRO-2035, a clearly 
worthwhile scanner. I don’t know that it 
beats the 2006, probably not, but it still 
has advantages, some pretty powerful. 

But, I want to continue to use the 2006 
for many years so this leads to the reason 
for my letter. Could you, during the next 
year when you have time & space in the 
WSR, list some recommended parts to 
buy and “stock” for the PRO-2006. I am 
concerned that parts might be 
discontinued in the future and some of us 
might want to get some spares to keep on 
hand. You know, the stuff that is only 
available from Tandy. 

ED: See my brief on page 5 this month 
for the PRO-2004! What timing! The 
PRO-2006 should be supported by Tandy 
for another 4-yrs, so there's no hurry, 
but your concern is certainly valid. Use 
my list for the PRO-2004 as a general 
guide and translate the part numbers to 
those for the PRO-2006 and you 'll have 
ample preparation. 

EL PANEL CONSIDERATIONS 

Does age still kill the display even if the 
light is seldom used? 


ED: Darn good question, and I don't 
know for sure. The EL Panel is electro- 
chemically active when 80-110 VAC is 
applied to it. Chemistry is one of those 
areas where age & environmental 
factors clearly play a role. I would 
advise spare EL Panels to be seal- 
wrapped and stored in the refrigerator, 
but there's little you can do for the one 
in the scanner short of keeping it off. 

After seeing how they illuminate the 
PRO-2035's LCD Display with LED's, I 
may try to work up a similar scheme for 
the PRO-2004/5/6 and 2021/2022, etc. 
Shouldn't be difficult, but we need a 
source of frosted glass or plastic in 
order to make it feasible . The LCD 
Display module is clear, as you may 
know. Bright LEDs behind clear glass 
would be obnoxious without something to 
diffuse and spread the light a little. 

List some tips to make the 2006 last 
forever, (joke! ©) 

ED: Serious business, if you ask me. 
The single best thing you can do is use 
12-14 vDC from an external power 
supply and don't use the AC supply. 
Otherwise, keep it clean and cool. It 
should last a long time and at least until 
its been antiquated by the next wave! 

Also the PRO-43 seems to be less 
sensitive than my other scanners. Can 
VHF low band sensitivity be improved? 
By me? If not, is there a technician I can 
send it to that might be able to help it a 
little? Other than this, I love the PRO- 
43 because what you hear is really there. 
Thanks for a great newsletter and keep 
those mods coming. 


ED: There's nothing you can do unless 
to undo something you may have done to 
wreck the sensitivity. Did you resolder 
the antenna wire inside after doing the 
cellular and other mods? Not doing so 
will be a killer on the sensitivity. There 
may be a way for you to perform a basic 
realignment with the aid of an S-Meter, 
but I haven't transcribed the procedures 
into layman's lingo yet and there has 
been no demand. If your PRO-43 isn V 
seriously hacked, I'd suggest sending it 
to a Radio Shack service center for an 
alignment. The antenna is important, 
though, and one cut for VHF-Lo will do 
more than anything to snag those elusive 
signals that you think you 're missing. 

NEXT ISSUE WILL BE LATE I 


Normally, we take June and December 
off. This one time, we're taking off in 
March. V5N3 will be mailed in late 
March or early April so as to give me the 
much needed time to finish my third 
book The Ultimate Scanner . We’ll be 
back on schedule by July with V5N6 
mailed in that time frame. We won’t 
take May off as is our usual custom. In 
no case will you miss any issues. 

| MY BOOK IS PROGRESSING I 

But the graphics and detail are incredibly 
slow and painstaking, much slower than for 
my first two books where quality was not the 
highest item on that publisher’s list of 
priorities. I have a new publisher now, who is 
the cat's meow for quality and doing things 
right. Since he’s that way, I can be no less so. 
Good things come in due time. Watchl © 


2/1/95 - 5.-47PM- The " World Scanner Report" © 1991-95; Volume 5, No 2; Page8 


COMMtronics ENGINEERING'S 
mSCMim REPORT” 
FO BOR 262178 
SAN DIEGO, CA 92196-2178 



950128V5N02P10 


Remember - Next Issue Will Be Late 


o TOCTT1? 




+ New: Scanner Circuit Analysis! PRO-2004/5/6 Low Batt Circuit Explained 
+ PRO-2004/5/6 Memory Battery Circuit Explained 
+ PRO-2004/5/6 Power Supplies Explained ~ Power Supply Modifications 
+ 900 MHz Cordless Phone Freqs for Panasonic & Reaslistic 
+ UPDATE: PRO-2004 Parts May Soon Be Gone! ~ BC-100/200XLT NiCd Packs 
+ Finding tilings in the PRO-2006 ~ Caller ID & Scanners? ~ Impossible Cellular Mods 
+ Cost of blue LEDs dropping ~ Note on Service Manuals ~ Exgtended Memory Mods 
+ Stocking up on parts ~ Electroluminescent Panel Considerations 
+ Next Issue will be one month late 
+ My Book is Progressing